Sharp PC-1500 - 3 U L581 J1;0 Port; 4 Circuit Description

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4. CIRCUIT DESCRIPTION
1
4-1 .. Chip Select Circuit
c
p
u
I/o
p
0
DM£1
DllEO
R
T
ME O
MEI
ADS
TC40Hl89F
TC 40Hl · 38F
VGG
so
To RAMS ( TC55 1? AF)
S I
52
Tu MOOJle Un il
sa
S7
Y4
Y5
Vss
Vss
n SG
vee
WEX
Th 1/ 0 Port
V2
To Oi Sp lay chip 1.3
L...... f---Q=va To Dis play <;l1ip2.4
'- - -- - - -- -+ To RAllj, 2( T C,:~~14r)
'- -- --- - ---- - - ---- - -+ To VO PORT( LH5810)
'--+To R0ll(CS6 13 1 28 F)
'- -- - --- ---- --- - - -- -•To MOOu l lh i t
'-- -- - --- - ---- - - -----+To Mcdvl lhit
tt .t ou 1i • Internal logic
Truth Table
VO
A
In put
EN A .BL! Sl>L1$CT
Output
Vi
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A
•
c
~ 2'.1
Y! VJ ...
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Y'1
L
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"
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.. H H II II II H II
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$F.LECT
Y2
•
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... ( ·
0 <:>
II II II II
"
II
II
" ... ..
"
(,;-
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~ II II II H II II II II
Vi
II L L L L L I.
" "
H II II II II
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Yi
II L L II
L L
II
L
II
II
II II
"
II
II
L
I. L
"
L
"
"
L H H
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II
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C l
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L L
"
H L !I II
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L
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"
II
"
L L I. L H II
"
II H L H H H
H
L L II
L
II II II
"
II II
L
II H
"
L L L H II II II H II II H L H
II L L II H H H II H H
"
II
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L
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